It is conventionally known a mobile printer including a container configured to contain a paper roll for example as a roll body into which a belt-shaped print medium is wound (see Japanese laid-open patent publication JP 2012-206278, for example). The printer described in the Japanese laid-open patent publication JP 2012-206278 is provided with a paper roll holder covered by a cover frame that is openable and closable at a rear side of the substantially box-shaped inside of a body frame. That is, it is described that the paper roll holder and the body frame are formed with a double-layered structure.